The piston crown has channel and large void cast into it through which the oil is circulated.
These are as close as possible to the side, top surface of the crown as well as behind the Piston rings to attain optimum cooling of the high fuel combustion temperatures.
The oil is drawn from the main engine sump by the Lube oil pump being discharged to the manifold bolted to the outside engine casing.
from there an internal swinging arm piping system supplies oil to the crosshead bearings and piston crown cooling.
Cooling oil enters from the central tube within the Piston rod and flows under the centre of crown before passing through bore cooling holes in radial direction to the toroidal space at the Piston edge, before returning through the Piston rod via small holes drilled into the Piston rod where it is collected in a tray at crosshead bearing.
Here,the oil temperature and viscosity monitored before spilling over the tray, cascading down into the main lube oil sump.